Recovery of alkyl lead compounds from their reaction masses



Patented Apr. 28, 1936 UNITED, STATES PATENT OFFICE RECOVERY OF ALKYL LEAD COMPOUNDS FROM THEIR REACTION MASSES Louis S. Bake, Pennsgrove, and Alfred E. Parmelee, Carneys Point, N. J., assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application March 30, 1933,

Serial No. 663,662

22 Claims.

This invention relates to the recovery of alkyl lead compounds from their reaction masses and more particularly to the recovery of tetra ethyl lead from its reaction mass by steam distillation.

In the present day commercial processes for manufacturing alkyl lead compounds and particularly tetra ethyl lead, a lead monosodium alloy is contacted with an alkyl halide such as ethyl chloride in a reaction chamber.

The reaction mixture thus obtained comprises an intimate mixture of unreacted lead sodium alloy, sodium,

chloride, lead and the alkyl lead compound. There is 2 to 3 times as much solid material comprising sodium chloride, lead and unreacted lead-sodium alloy as there are alkyl lead compounds.

The alkyl lead compound is adsorbed lead compound remain adsorbed on the lead par-,

ticles which also tend to agglomerate. This adsorbed and occluded alkyl lead compound cannot be removed by extending the timev of the distillation.

In order to improve the recovery of the lead alkyl compound from the reaction mass it has been proposed to add, to the reaction mass in the still, wetting and dispersing agents which prevent agglomeration of the lead in the mass and permit a more complete recovery of the alkyl lead compound. While this latter process has proved to be very successful in operation, it has been foundthat substantial amounts of the alkyl lead compounds are not removed from the reaction mass but remain adsorbed upon the particles of lead. The lead sludge remaining from such a process will normally contain from 1 to 4% of the alkyl lead compound adsorbed on the lead.

An object of the present invention is to provide a new method for recovering alkyl lead compounds from reaction masses or lead sludges containing the same. A still further object is to provide a process whereby almost theoretical recovery of alkyl lead compounds are obtained from i the reaction masses.

Other objects are to ad- Vance the art. hereinafter.

These objects may be accomplished in accordance with my invention which comprises neutralizing either wholly or partially the alkali'in the reaction mass or lead sludge and then distilling by steam in accordance with the usual process. 7

We have found that, when an acid reacting substance is added to a reaction mass or lead sludge, containing alkyl lead compounds, in such amounts that the alkalinity of the reaction mass or sludge is reduced to a pH of not lower than 7 and then the reaction mass or lead sludge is subjectedto steam distillation in accordance with the usual custom, almost theoretical recovery of the organic lead compound is obtained. Among the acid reacting substances which we have found to operate most satisfactory for our purposesare sulfuric acid, acetic acid, phthalic acid, ammonium sulphate, ammonium acetate and the like.

Preferably, the acid reacting substances should be employed in an amount sufiicient to reduce the alkalinity of the reaction mass or sludge toa pH of between 7 and 8. However, smaller amounts of the acid reacting substances may be employed and we have found that satisfactory results may be obtained when sufficient of the acid reacting substance is employed to reduce the pH of the reaction mass or sludge to between 7 and 11. It is undesirable to reduce the pH of the reaction mass or sludge to below 7.0 as the ex-' cess acid tends to decompose the alkyl lead compounds although complete removal of the alkyl lead compound from the reaction mass or lead sludge may be obtained by employing excess of the acid reacting substance.

The acid reacting substance may be added to the reaction mass at the start of or during the distillation or at the end of a straight steam distillation followed by further distillation to remove the alkyl lead compound released from the sludge by coagulation of the lead.

In order to more clearly illustrate our invention, the preferred mode of carrying the same into efiect and the advantageous results to be obtained thereby, the following examples are given;

Still other objects will appear E a Z mmp e1 Upon analysis, it was found that 8.4 partsor f 3.4% of tetra ethyl lead remained in the lead sludge. r

' Example 2 100 parts of a reaction mass, similar to that treated in Example 1, was. added to 300 parts of water containing 0.2- parts' of Turkey red oil.

This mixture was then subjected to steam distillation in the usual manner. Was-found that 3.2 parts or 3.2% of tetra ethyl 7 lead was retained by thesludgeh Example 3 100 parts of a reaction mass similar to that 7 Example 4 100 parts of a reaction mass, similar to that treated in Example 1, .Wasadded to 300 parts of Water.'- To the resulting mixture, was added sulfuric acid in an amount sufficient to reduce the pH to" 9l3. Thismixture was then subjected to steam distillation as in the preceding examples.

After suchdistillation, it was found that the lead sludge retained 0.35% of tetra ethyl lead. Example 5 V The experiment of Example 3 was repeated except that ammonium sulfate was employed in place of the sulfuric acid. As a result, 0.19% of'tetra ethyl flead was retained in the sludge;

Example 6 The experiment of Example was repeated employing ammonium sulfate in place of the sulfuric acid; The lead sludge, remaining after the distillation, contained 0.26% tetra ethyl lead.i

' Example 7 7 "100' parts or a reaction mass, similar to that treated in Example 1, was added to 300 parts of Water. Acetic acid was then added to the resulting mixture until the pH was reduced to 7.5 and the resulting mixture subjected to steam dis tillation in the usual manner. it was found that 0.17% of tetraethyl lead remained in the sludge.

Example 8 The experiment of Example 7 was repeated employing a smaller amount of acetic acid so that the pH of the mixture was reduced to only 9.3.

After distillation 0.42% tetra, ethyl lead was found to have been retained by the lead sludge.

Eram'ple 9 a A'raction mass,-obtained by reacting ethyl chloride With monosodium lead alloy, was subjected to a steam distillation. After distillation, it was found that the'still residue or lead sludge contained;2.9% of tetra .ethyllead. 'l00 parts of 'this still residue or sludge 'was redistilled.

After such redistillation, 2.7% of tetra ethyl lead was found in the sludge. Another 100 parts of the still residue or sludge, containing 2.9% of tetra ethyl lead, was slightly acidified with sul furic acid and thenjredistilled with the removal Upon analysis, it

be employed in our process.

After distillation,

of all but 0.09% of the tetra ethyl lead from the sludge. 1 r 7 From. the above examples, it 'will be apparent thatthe acid reacting substances and the amounts thereof employed maybe rather widely varied. Other. acid reacting substances which may 'be' mentioned are hydrochloric acid, butyric acid, oleic acid, stearic acid, sulfonic acids and the like.

The acid reacting substances may be employed either with or Without Wetting and dispersing agents. For example, an'alkyl lead reaction mass may be added to water. and then the pH of the fmixtureadjusted by means of the acid substances or the reaction mass may be added to Water containing wetting and dispersing agents such as are 7 disclosed in Patent 1,645,375 issued to Daudt et al.

and the copending application of Downing, Parmelee, Pedersen & Stecher, Serial No.'597,800 filed on or about March 9, 1932 and the pH adjusted by adding anacid substance. In other words, the processes disclosed in the aforesaid patent and application may be employed modifying them by adding acid substances in accordance with my invention. Among. the wetting and dispersing agents disclosed by Daudt et al. and which may be employed in my process are glue, agar-agar, Turkey red oil, engine oil,-lard oil, benzene, toluene,

sodium sulfide, sodium carbonate, sodium sulfate,

' sodium sulfite, sodium sulfiite and engine oil, and

the like. Downing et al. in their application above identifieddisclose as wetting and dispers ing agents engine oil and thiocarbanilide, sodium chromate, sodium dichromate, sodium thiosulfate, sodium silicates, sulfonated castor oils as Turkey redoil and monopole oil, salts of alkyl naphthalene sulfonic acids, condensation products of naphthol sulfonic acids and formaldehyde, reaction products of oleic acid and aliphatic diamines, the higher fatty and unsaturated acids and their soaps, resinates, and the like which may From the foregoing description of our invention it will be readily apparent to those skilled in the art that many changes and modifications may be made in the process and the ingredients employed without departing from the spirit'of our invention; Accordingly, the scope of our invention is to be limited solely bythe appended claims construed as broadly as is permissible in view of the prior art. r r

We claim: r r n r 1. The process of recovering tetra alkyl lead from a reaction mass or lead sludge'c'ontaining the same and unreacted lead-sodium alloy which comprises steam distilling the tetra alkyl lead in the presence of an acid reacting compound in an amount sufficient to materiallyreduce the alkalinity of the sludge to a pH of not lower than 7.0.

-2. The process of recovering tetra alkyl'lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises steam distilling the tetra alkyl lead in the presence of an acid reacting compoundin an amount sufficient to reduce the alkalinity'of. the

sludge to apH of between 7.0 and 11.

3. The process of recovering tetra alkyl lead from a reaction mass or lead's ludge containing the same and unreacted lead-sodium alloy which comprises steam distilling the tetra alkyl lead in the presence of an: acid reacting compound in an amount sufficient to reduce the alkalinity of the sludge'to a pH of between 7.0 and 8. 5'

4. The process of recovering tetra alkyl lead from a reaction mass, or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixingthe reaction mass or sludge with water and an acid reacting compound sufficient in amount to materially reduce the alkalinity of the mixture'to a pH of not lower than 7.0 and then subjecting the mixture to steam distillation.

5. The process of recovering tetra alkyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water and an acid reacting compound suificient in amount to reduce the alkalinity of the mixture to a pH of between 7.0 and 11 and then subjecting the mixture to steam distillation.

6. The process of recovering tetra alkyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water and an acid reacting compound sufficient in amount to reduce the alkalinity of the mixture to a pH of between 7.0 and 8 and then subjecting the mixture to steam distillation. V

7. The process of recoveringtetra alkyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water, a wetting and dispersing agent, and an acid reacting compound sufiicient in amount to materially reduce the alkalinity of the mixture to a pH of not lower than 7.0 and then subjecting the mixture to steam distillation.

8. The process of recovering tetra alkyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water, a wetting and dispersing agent, and an acid reacting compound suflicient in amount to reduce the alkalinity of the mixture to a pH of between 7.0 and 11 and then subjecting the mixture to steam distillation.

9. The process of recovering tetra alkyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water, a wetting and dispersing agent, and an acid reacting compound sufficient in amount to reduce the alkalinity of the mixture to a pH of between 7.0 and 8 and then subjecting the mixture to steam distillation.

10. The process of recovering tetra ethyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water and an acid reacting compound sufficient in amount to materially reduce the alkalinity of mixture to a pH of not lower than 7.0 and then subjecting the mixture to steam distillation.

11. The process of recovering tetra ethyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water and an acid reacting compound suflicient in amount to reduce the alkalinity of the mixture to a pH of between 7.0 and 11 and then subjecting the mixture to steam distillation.

12. The process of recovering tetra ethyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water and an acid reacting compound sufficient in amount to reduce the alkalinity of the mixture to a pH of between 7.0 and 8 and then subjecting the mixture to steam distillation.

13. The process of recovering tetra ethyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water, a wetting and dispersing agent, and an acid reacting compound suflicient in amount to materially reduce the alkalinity of the mixture to a pH of not lower than 7.0 and then subjecting:

the mixture to steam distillation.

14. The process of recovering tetra ethyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water, a wetting'and dispersing agent, and an acid reacting compound suflicient in amount to reduce the alkalinity of the mixture to a pH of between 7.0 and 11 and then subjecting the mixture to steam distillation.

15. The process of recovering tetra ethyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water, a wetting and dispersing agent, and an acid reacting compound suflicient in amount to reduce the alkalinity of the mixture to a pH of between 7.0 and 8 and then subjecting the mixture to steam distillation.

16. The process of recovering tetra alkyl lead from a mixture of tetra alkyl lead, lead-sodium alloy, sodium chloride and lead which process comprises the step of steam distilling the tetra alkyl lead in the presence of an acid reacting compound in an amount suflicient to materially reduce the alkalinity of the mixture to a pH of not lower than 7.0.

17. The process of recovering tetra' alkyl lead from a mixture of tetra alkyl lead, lead-sodium alloy, sodium chloride and lead which process comprises the step of steam distilling the tetra alkyl lead in the presence of an acid reacting compound in an amount suflicient to reduce the alkalinity of the mixture to a pH of between about 11 and 7.0.

18. The process of recovering tetra alkyl lead from a mixture of tetra alkyl lead, lead-sodium alloy, sodium chloride and lead which process comprises the step of steam distilling the tetra alkyl lead in the presence of an acid reacting compound in an amount suflicient to reduce the alkalinity of the mixture to a pH of between about 8 and 7.0.

19. The process of recovering tetra ethyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludgewith water, a wetting and dispersing agent, and sulfuric acid suflicient in amount to reduce the alkalinity of the mixture to a pH of between 7.0 and 11 and then subjecting the mixture to steam distillation.

20. The process of recovering tetra ethyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water, a wetting and dispersing agent, and ammonium sulfate sufiicient in amount to reduce the alkalinity of the mixture to a pH of between 7.0 and 11 and then subjecting the mixture to steam distillation.

21. The process of recovering tetra ethyl lead from a reaction mass or lead sludge containing the same and unreacted lead-sodium alloy which comprises mixing the reaction mass or sludge with water, a wetting and dispersing agent, and a carboxylic acid sufficient in amount to reduce the alkalinity of the mixture to a pH between 7.0 and 4 r r 7 2,0 9,703 V 7 i1 and then subjecting the mixture to steam disacetic acid sufilcient in amount to reduce the tillation. r 7 alkalinity of the mixture to a;pHofbetween 7.0 22. The process of recovering tetra ethyl lead and 11 and then subjecting the mixtiii'e to steam from a. reaction mass or lead sludge containing distillation. V r v the same and unreacted lead-sodium alloy which 7 V LOUIS S. BAKE.

' comprises mixing the reaction mass or sludge ALFRED E. PARMELEE'.

with water, a wetting and dispersing agent, and 

